TiO2 nanoparticles, doped with di erent Pt contents, were prepared by a modified photodeposition method using Degussa P-25 TiO2,
H2PtCl6 6H2O and methanol as the solvents. The physicochemical properties of Pt/TiO2 were investigated by the nitrogen adsorption
and desorption isotherm measurement technique, X-ray di raction analysis and photoluminescence spectra, respectively. Reaction rates
from photocatalytic removal of dichloromethane over Degussa P-25 TiO2 and Pt/TiO2 were evaluated. The average diameter and BET
surface area of the TiO2 catalyst particles were 300 nm and 50 m2/g, respectively. The degradation e ciency was 99.0%, 82.7%, 55.2%,
and 57.9% with TiO2 at inlet concentrations of 50, 100, 200, and 300 ppm, respectively. And the degradation e ciency was 99.3%,
79.7%, 76.5%, and 73.4% with a 0.005 wt.% Pt/TiO2 at inlet concentrations of 50, 100, 200, and 300 ppm, respectively. In addition, we
found that the photoluminescence emission peak intensities decreased with increases in the doping amount of Pt, which indicates that
the irradiative recombination was weakened. Furthermore, the results showed that the UV/0.005 wt.% Pt/TiO2 process was capable of
e ciently decomposing gaseous DCM in air. 相似文献
The present work focuses on the fate of two cancerostatic platinum compounds (CPC), cisplatin and carboplatin, as well as of two inorganic platinum compounds, [PtCl4]2− and [PtCl6]2− in biological wastewater treatment. Laboratory experiments modelling adsorption of these compounds onto activated sludge showed promising specific adsorption coefficients KD and KOC and Freundlich adsorption isotherms. However, the adsorption properties of the investigated substances were differing significantly. Adsorption decreased following the order cisplatin > [PtCl6]2− > [PtCl4]2− > carboplatin. Log KD-values were ranging from 2.5 to 4.3 , log KOC from 3.0 to 4.7.
A pilot membrane bioreactor system (MBR) was installed in a hospital in Vienna and fed with wastewater from the oncologic in-patient treatment ward to investigate CPC-adsorption in a sewage treatment plant. During three monitoring periods Pt-concentrations were measured in the influent (3–250 μg l−1 Pt) and the effluent (2–150 μg l−1 Pt) of the treatment plant using ICP-MS. The monitoring periods (duration 30 d) revealed elimination efficiencies between 51% and 63% based on averaged weekly input–output budgets. The derived log KD-values and log KOC-values ranged from 2.4 to 4.8 and from 2.8 to 5.3, respectively. Species analysis using HPLC-ICP-MS proofed that mainly carboplatin was present as intact drug in the influent and – due to low log KD – in the effluent of the MBR. 相似文献
The NO/H2/O2 reaction was studied under oxidizing conditions in the 100-400 °C range over 0.1 wt% Pt supported on various metal oxides such as MgO, CeO2, SiO2, La2O3, CaO, Y2O3 and TiO2. The Pt/MgO and Pt/CeO2 catalysts showed good catalytic behaviours. Here, we find that the Pt/Mg-Ce-O catalyst, prepared from MgO and CeO2 by the sol-gel method, is a very active and selective catalyst towards N2 formation in the whole 100–400 °C range. This catalyst appears to be the most active, selective and stable one ever reported in the literature for the NO/H2/O2 reaction, even in the presence of 5%v H2O or 20 ppmv of SO2 in the feed stream.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic. 相似文献
Intention, Goal, Scope, Background Following the introduction of automobile catalytic converters the platinum group metals (PGM) platinum (Pt), palladium (Pd)
and rhodium (Rh) gain on increasing interest in environmental research as these metals are emitted with exhaust fumes into
the environment. Consequently, elevated PGM levels were found in different environmental matrices uch as road dusts, soils
along heavily frequented roads, sediments of urban rivers etc. Accordingly, the effects of increasing PGM emissions on the
biosphere are controversially discussed.
Objective This paper summarizes the present knowledge on the biological availability of PGM to plants and animals. As biological availability
is one of the most decisive factors determining the toxicologi-cal potential of xenobiotics, this information is very important
to evaluate the possible threat of the noble metals to ecosystems.
Results and Discussion The availability of soluble as well as particle bound PGM to terrestrial plants was demonstrated in several studies. Experimental
investigations revealed uptake of Pt, Pd and Rh also by aquatic plants. Additionally, the biological availability of the noble
metals for animals has been verified in experimental studies using soluble metal salts, catalytic converter model substances,
sediments of urban rivers, road dust or tunnel dust as metal sources. These studies refer mainly to aquatic animals. Beside
of free living organisms, in particular worms parasitizing fish demonstrated a high potential to accumulate PGM. This could
be of great interest in respect of biomonitoring purposes. Generally, for plants as well as for animals Pd turns out to be
the best available metal among the PGM. Compared to other heavy metals, the biological availability of PGM from road dust
to zebra mussels(Dreissena polymorpha) ranged between that of Cd and Pb.
Conclusion Especially chronic effects of PGM on the biosphere can not be excluded due to (1) their cumulative increase in the environment,
(2) their unexpected high biological availability and bioaccumulation and (3) their unknown toxicological and ecotoxicological
potential. However, it appears that acute effects on ecosystems due to anthropogenic PGM emission are not likely.
Recommendation and Outlook Research on environmental PGM contamination of the biosphere, especially the fauna, and on long-term toxiciry of low PGM concentrations
is highly appreciated. These studies require very sensitive analytical techniques to determine PGM even in low sample amounts.
Research has to be done in particular on reliable determination of (ultra) trace levels of Pd and Rh as the lack of data on
these two metals is mainly due to analytical problems. 相似文献
In order to search the degradability of kraft lignin, the potential bacterial strains Bacillus subtilis (GU193980) and Klebsiella pneumoniae (GU193981) were isolated, screened and applied in axenic and co-culture conditions. Results revealed that mixed culture showed better decolorization efficiency (80%) and reduction of pollution parameters (COD 73% and BOD 62%) than axenic culture. This indicated syntrophic growth of these two bacteria rather than any antagonistic effect. The HPLC analysis of degraded samples of kraft lignin has shown the reduction in peak area compared to control, suggesting that decrease in color intensity might be largely attributed to the degradation of lignin by isolated bacteria. Further, the GC–MS analysis showed that most of the compounds detected in control were diminished after bacterial treatment. Further, the seed germination test using Phaseolus aureus has supported the detoxification of bacterial decolorized kraft lignin for environmental safety. All these observations have revealed that the developed bacterial co-culture was capable for the effective degradation and decolorization of lignin containing rayon grade pulp mill wastewater for environmental safety. 相似文献
A rapid, simple and sensitive method was demonstrated for the determination of phenolic compounds in water samples by alternating-current oscillopolarographic titration. With the presence of sulfuric acid, phenol could be transferred into a nitroso-compound by reacting with NaNO2. The titration end-point was obtained by the formation of a sharp cut in the oscillopolarographic with infinitesimal NaNO2 on double platinum electrodes. The results showed that phenol concentration had an excellent linear relationship over the range of 4.82×10-6-9.65×10-3 mol/L, the RSD of the proposed method was lower than 1.5%, and the spiked recoveries of three real water samples were in the range of 95.6%-106.9%. 相似文献